Having a high second order intercept point (IIP2) in a wireless communication receiver can be an important characteristic that determines how well the receiver performs in circumstances where there might be significant interference entering the receiver, e.g., transmit signal leakage.
For example, when operating in full duplex, as may be the case when operating under the Wideband Code Division Multiple Access (WCDMA) standard, a direct conversion receiver may need to have a very high second order intercept point (IIP2) due to transmit signal leakage. As another example, with a handset incorporating a low-IF Global System for Mobile Communications (GSM) receiver that can receive a GSM signal while also transmitting a Code Division Multiple Access (CDMA) signal, a high IIP2 may be needed to prevent the CDMA signal from be down-converted/demodulated into the low-IF GSM receiver. As yet another example, a high IIP2 may be needed when a CDMA transmitter is transmitting in close proximity to an active GSM receiver.
High IIP2 can be difficult to maintain in receivers (such as direct conversion receivers and low-IF receivers) because IIP2 can be very sensitive to manufacturing variations and operating conditions like supply voltage, local oscillator (LO) power and or frequency, and temperature.